TreeFlex is an open source org-chart-style tree package.  

It's really handy for showing parent-children relationships in your data, and is easier for users to interpret than a TreeView (which is also there) because siblings are horizontally spaced.

But I've also made it interactive, clicking on a node activates your EWB code, so you can use the TreeFlex as a selector for representing non-linear data.

These are all available in my Nice controls at
  https://erickengelke.com/nice/samples.html

Erick
EWB Programming Books and Component Library
http://www.erickengelke.com